The present invention is with respect to surface boxes for gate valves with operating rods as fitted to underground piping, more specially water pipes, with a tube-like supporting frame and rod guard sleeve placed therein so that it is supported in relation to the frame by a thrust screw.
An account of a known design of such surface boxes is to be seen in the German Offenlegungsschrift specification No. 2,910,598. They are used for housing the driving rod of a gate valve fitted to piping laid under the ground so that when desired the cover of the box may be opened and the rod may be worked for opening or shutting the valve. In the case of the known surface box the rod guard sleeve in the supporting frame is controlled in its position therein by a thrust screw so that the rod guard sleeve may be moved lengthways and changed in position without moving the supporting frame in order to make allowances for settlement of the highway or for other purposes. However, it has been seen from experience that such a surface box has a number of shortcomings which might be taken care of, even though the design generally is not without its useful effects. In fact, one trouble likely to be experienced with such surface boxes is that the weight of vehicles driving over the box is the cause of great static and dynamic forces that have to be taken up by the surface box and transmitted to the foundation so that the rod guard sleeve is likely to be pushed sideways. Furthermore, the thrust screw will then no longer be at the right position of adjustment, this in turn being likely to be responsible for damage to the valve operating rod placed inside the supporting frame. At the same time there will be the further danger of the level of the rod guard sleeve in relation to the supporting frame changing so that the surface box will no longer be lined up with the surface of the highway.